From The Company: The Rise and Fall of the Hudson's Bay Empire, by Stephen Bown (Doubleday Canada, 2020), Kindle pp. 358-359:
WILLIAM ASHLEY, AN ASTUTE ENTREPRENEUR, gunpowder salesman and later politician based out of St. Louis, changed the fur trade forever in the Pacific Northwest and set in motion events that would change its politics as well. In the spring of 1823, Ashley and his partner Andrew Henry organized a band of one hundred ragged and unruly ramblers—some wastrels, some thugs, some adventurous youths from the east, and quite a few former Nor’Westers disgruntled after the amalgamation with the Hudson’s Bay Company in 1821. Ashley’s small band, based out of the ramshackle tavern town of St. Louis, poled their unwieldy flat-bottomed barges upriver along the mud-coloured Missouri River and into the mountains. From there they filtered into the valleys and gulches of western Montana, Idaho, Wyoming and Colorado to set traps for unwary beaver. They were the first American “Mountain Men,” and during the 1820s and 1830s they expanded their operations westward toward the Pacific, nibbling at the fringes of McLoughlin’s domain and encroaching on the traditional lands of the Indigenous peoples.
Ashley’s “One Hundred Men” were not hauling into the wilderness back-breaking burdens of trade goods to exchange with the Indians for their furs. Instead they were laden with beaver traps and personal supplies. They had no intention of constructing a trading fort in the mountains. Ashley’s scheme was to have his men do the actual trapping—a role in the fur trade that had previously been the exclusive domain of Indigenous peoples, particularly in the north.
Not surprisingly, the invasion of traditional territories did not help relations between the two peoples. The various tribes didn’t appreciate hundreds of foreigners wandering around their territory trapping all the beaver. Within a few years, a more or less constant low-level war existed between the new trappers and the natives. Both the Mountain Men and the Indigenous warriors proudly displayed the scalps of their vanquished foes, sometimes wearing strings of the shrivelled flesh and hair as accoutrements to their outfits. The American senator Thomas Benton suggested that nearly five hundred American trappers perished in combat with the Rocky Mountain peoples by the close of the 1820s. He made no estimate of the Indigenous peoples that they had killed. The life expectancy of a “free trapper” could be short, and so for mutual protection as they invaded the traditional lands of proud and sometimes militant nations of the Blackfoot Confederacy and the Snake (Shoshoni) or Nez Perce, the free trappers travelled in brigades, or companies, of twenty men or more. Two of the greatest of these brigades were the Rocky Mountain Fur Company and the Missouri Fur Company, although both were later absorbed by the American Fur Company as John Jacob Astor tightened his grip on the American fur trade in the 1830s. Astor rapidly increased the trade along the upper Missouri River with the use of steam-powered ships. By the time the demand for fur had petered out by the 1840s, Astor had sold his interests in the fur trade, and the industry slipped into decline—the age of the Mountain Men was between 1822 and 1840. But the American Fur Company continued to flourish in the decades to follow, beginning the lucrative trade in bison hides that eventually drove the thundering herds to near extinction later in the century.